<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <button id="btn">单击</button>
</body>
<script>
    document.getElementById('btn').onclick = function () {
        test()  // test.caller: btn
    }
    function test () {
        console.dir(test.caller);
        // console.dir(test.caller.arguments);
    }
    // test()   test.caller: null
</script>
</html>